Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
A piezoelectric device can be used to generate electrical power when a mechanical force is applied on it. For example, a piezoelectric device may include a stack of thin layers of piezoelectric materials, such as quartz, tourmaline, plumbum zirconate titanate (PZT), plumbum magnesium niobate (PMN), etc., and thin metallic electrode layers interposed between the piezoelectric material layers. The electrode layers of the piezoelectric device can be connected in series to increase the combined voltage or connected in parallel to increase the current. Also, the electrical power generated by the piezoelectric device can be provided in AC or DC form, which can be stored in an electrical storage device such as a capacitor.
Some piezoelectric devices typically can have a resonant characteristic in converting a mechanical force into an electrical power. Thus, when the mechanical force makes the piezoelectric device operate out of such resonant characteristic, the power generation efficiency may be deteriorated.